At what temperature do icing conditions exist in flight when in visible moisture?

Icing conditions in flight, particularly when visible moisture is present, are typically observed in temperatures at or below 10°C. At these temperatures, the possibility of liquid water existing in clouds or precipitation increases, which can lead to ice accumulation on aircraft surfaces, especially on wings and control surfaces where airflow disruption can occur.

When temperatures are at or below 10°C, the conditions are conducive for icing, and specific aircraft icing reports often note that even in temperatures above freezing, if moisture is present (like in clouds or rain), there is still a risk of ice forming if the aircraft is operating in the right conditions. As the aircraft temperature drops to 0°C or lower, the risk of icing becomes even more significant.

Conversely, temperatures above 10°C typically do not present a risk for icing, as any moisture present is likely to be in a liquid state without the conditions for accumulating ice. Hence, the correct choice reflects the recognized guidelines for pilots concerning icing risks during flight operations.